1. Field of the Invention
The subject invention generally relates to expanding diameter alignment pins and fasteners and more specifically to an alignment pin or fastener that clamps both radially and axially.
2. Description of Related Art
In many manufacturing processes, such as machining and welding, fixtures are often used to accurately position and hold the work piece to a worktable. Worktables often have an array of holes that allow specially designed fasteners or alignment pins to quickly and accurately fasten the fixtures and/or the work piece to the table. Common examples of such fasteners or pins include collets, ball lock pins, and adjustable diameter bolts. Such devices can be used not only for attaching fixtures and work pieces to tables, but they may also be used for other applications as well. Although the devices may have broad application, they do have their drawbacks.
Collets, typically include a threaded rod that screws into a tapered piece, which forces the exterior of the collet to expand radially as the threaded rod is tightened. Collets typically clamp and align in just a radial direction without providing any significant axial clamping. In some cases, operation of a collet requires access to both ends of the collet, which is not always available.
Ball lock pins usually comprise a screw that threads into a hollow pin. As the screw turns into the pin, the screw forces one or more balls radially outward from inside the pin. When the pin is inserted into a hole of some part, the radially protruding balls press against the part to hold the pin in place. Depending on the design, such ball lock pins have limited ability to clamp and align. Also, such pins usually include several precise parts that can be expensive to make and difficult to maintain in good operating condition. Moreover, actuating ball lock pins usually require many turns of the screw before the balls fully engage. This can take time, which is limited in high production applications. Lastly, in order for a ball lock pin to accurate align two parts, the parts themselves need to be accurately machined, which can be expensive.
An adjustable diameter bolt, as disclosed in U.S. Pat. No. 5,284,408 and other patents by Duran; comprises a series of internally actuated collets. Such a bolt includes several relatively small parts that may jamb when exposed to dirty environments such as welding or machining.
Consequently, a need exists for a quick-actuating alignment pin that can clamp radially and axially, and do so with only having to access one end of the pin.